The invention relates to an axial lead semiconductor device, and especially to an inexpensive bridge rectifier device with an integral pulse suppressor chip, which is connected to protect electronic components from damage by large line overvoltages applied between the axial leads.
Axial lead semiconductor devices are well known, but their use has usually been limited to "packaging" of single chip diodes, which are solder-connected by means of preforms between two "nail head" or disc structures that are respectively attached to two opposed straight wire leads extending from the axial lead semiconductor devices. The two leads are coaxial, and extend in opposite directions from the package material (typically glass or ceramic) in which the semiconductor chip and the nail head or disk portions of the structure are encapsulated. In some instances, several individual chips solder-connected together in series fashion have been encapsulated in axial lead devices of the type mentioned above.
Simple axial lead semiconductor devices are popular because they are reliable and inexpensive to manufacture. Their low cost is partly due to the fact that the carriers or "boats" which are used in their manufacture are capable of holding large numbers, typically 1,000, of the axial lead devices during manufacture thereof. Conventional techniques are used utilizing vacuum pickup devices to place the individual solder preforms and semiconductor chips in cylindrical holes in which the bottom axial lead members are dropped so that the upper disk surfaces are horizontal. After the lower axial lead members, solder preforms, semiconductor diodes, and upper axial lead members have been positioned in the various holes in the boat, it is placed in an oven and its temperature is raised high enough to melt the solder preforms and thereby produce the desired electrical and mechanical interconnection of these elements. The boat is then removed from the oven, and the axial lead devices are then encapsulated, typically by transfer molding procedures.
However, the above described axial lead device structure has not been commonly used for assembly between the two disks of more than one semiconductor chip in side-by-side relationship because this technique would cause a great deal of difficulty in achieving convenient alignment of the solder preforms and the individual semiconductor chips. In no case has this technique been utilized for encapsulating multiple "stacks" of semiconductor chips in which intermediate conductive nodes need to be interconnected, because of the impracticality of positioning and soldering the various semiconductor chips and inter-node conductors that would be needed.